1. Field of the Invention
The present invention relates to a socket for an electrical part for detachably holding an electrical part such as a semiconductor device (called as "IC package" hereinafter).
Particularly, the present invention relates to a socket for an electrical part, which is adapted to prevent a contact portion of a contact pin from being stuck to a solder ball that is a terminal of the electrical part.
2. Description of the Related Art
As a conventional "socket for electrical parts" of this kind, there is provided an IC socket for detachably holding an IC package as "electrical part".
The IC package includes a BGA (Ball Grid Array) type of IC package which has a rectangular-shaped package body and a large number of solder balls mounted on a bottom surface of the package body.
Moreover, a contact pin is disposed to the IC socket and, to the contact pin, a pair of elastic pieces is formed. A contact portion is formed to one end portion of each of the elastic pieces so as to be contacted to a side portion of the solder ball and separated therefrom. One of the paired elastic pieces is pressed by a movable plate sliding in a horizontal direction to be elastically deformed thereby
When the movable plate is slid from an original position so as to elastically deform one of the paired elastic pieces, an interval (distance or gap) between both of the contact portions of both of the elastic pieces is widened so that the solder ball is inserted into the interval of both of the contact portions.
After the inserting work, the movable plate is returned to the original position so that the contact portion of one of the paired elastic pieces is returned to an original position at which no pressing force by the movable plate is applied, whereby the solder ball is clamped by both of the contact portions to electrically connected thereto.
In a state that the solder ball of the IC package and the contact portions of the paired elastic pieces of the IC socket are electrically connected, for example, a burn-in test is carried and, thereafter, similarly to the operation mentioned above, the movable plate is slid so as to elastically deform one of the paired elastic pieces, thereby widening the interval between both of the contact portions of both of the elastic pieces.
As a result of widening the interval between both of the contact portions of the paired elastic pieces, both of the contact portions thereof are separated from the solder ball and, thereafter, the IC package is removed from the IC socket with an automatic machine.
In this structure of the IC socket, by only sliding the movable plate, it is possible to mount the IC package on the IC socket and remove it therefrom without using inserting and extracting force, thereby improving mounting and removing working efficiency of the IC package.
However, in the conventional IC socket, while carrying out the burn-in test, the IC package is heated at approximately 125.degree. C. so that the solder ball gets to be softened to frequently be stuck to at least one of the contact portions.
In a state that the solder ball is stuck to at least one of the contact portions, when deforming one of the paired elastic pieces to widen the interval between both of the contact portions, in some cases, the solder ball is not separated from at least one of the contact portions with being stuck thereto.
In some cases where the solder ball is not separated from at least one of the contact portions, there is the possibility that it is impossible to remove, with the automatic machine, the IC package from the IC socket without using extracting force.